A young star-forming galaxy atz= 3.5 with an extended Lyman α halo seen with MUSE

Abstract

A young star-forming galaxy at z = 3.5 with an extended Lyman α halo seen with MUSE ABSTRACTSpatially resolved studies of high redshift galaxies, an essential insight into galaxy formation processes, have been mostly limited to stacking or unusually bright objects. We present here the study of a typical (L * , M = 6 ×10 9 M ) young lensed galaxy at z = 3.5, observed with MUSE, for which we obtain 2D resolved spatial information of Ly α and, for the first time, of C iii] emission. The exceptional signal-to-noise of the data reveals UV emission and absorption lines rarely seen at these redshifts, allowing us to derive important physical properties (T e ∼15600 K, n e ∼300 cm −3 , covering fraction f c ∼ 0.4) using multiple diagnostics. Inferred stellar and gas-phase metallicities point towards a low metallicity object (Z stellar = ∼ 0.07 Z and Z ISM < 0.16 Z ). The Ly α emission extends over ∼10 kpc across the galaxy and presents a very uniform spectral profile, showing only a small velocity shift which is unrelated to the intrinsic kinematics of the nebular emission. The Ly α extension is ∼4 times larger than the continuum emission, and makes this object comparable to low-mass LAEs at low redshift, and more compact than the Lyman-break galaxies and Lyα emitters usually studied at high redshift. We model the Ly α line and surface brightness profile using a radiative transfer code in an expanding gas shell, finding that this model provides a good description of both observables.

The MUSE Hubble Ultra Deep Field Survey

“…(1) Baldry et al (2014); (2) Bacon et al (2015); (3) this work; (4) Patrício et al (2016). See also http://classic.sdss.org/dr5/algorithms/spectemplates/ for templates No.…”

The Strong Gravitationally Lensed Herschel Galaxy HLock01: Optical Spectroscopy Reveals a Close Galaxy Merger with Evidence of Inflowing Gas

“…Rix et al (2004), and later on Sommariva et al (2012) showed that several blends of stellar UV photospheric absorption lines can be used to trace the metallicity of young stars, by measuring equivalent widths of these blends in specific wavelength windows. These metallicity indicators have been successfully applied in several works (e.g., Quider et al 2009Quider et al , 2010Patrício et al 2016), using high S/N spectra due to the faintness of these absorption lines. They are defined as the F1370, F1425, F1460, F1501, and F1978 indices, and their wavelength windows are shown in Figure 2 (except for the latter one which is not covered by our data).…”

Absorption-Line Spectroscopy of Gravitationally Lensed Galaxies: Further Constraints on the Escape Fraction of Ionizing Photons at High Redshift

“…In compiling the data for Figure 9, we include observations at redshifts z<4 from Jones et al (2013) (not shown in Table 1), Reddy et al (2016), and Patrício et al (2016). Across this increased redshift range, the figure shows that we cannot yet detect any significant time dependence.…”

“…The color scheme follows that in Figure 8. The black error bar and the black data point show f cov,obs derived from lowionization absorption profiles, in a stacked spectrum of z∼3 galaxies from Reddy et al (2016) and in a spectrum of a lensed z = 3.5 galaxy from Patrício et al (2016), respectively.…”